Unravelling the knotty problem of the Sun’s activity

Simulation of twisted magnetic field lines emerging through the photosphere, the visible surface of the Sun.
D. MacTaggart et al.

A new approach to analysing the development of magnetic tangles on the Sun has led to a breakthrough in a longstanding debate about how solar energy is injected into the solar atmosphere before being released into space, causing space weather events. The first direct evidence that field lines become knotted before they emerge at the visible surface of the Sun has implications for our ability to predict the behaviour of active regions and the nature of the solar interior. Dr Christopher Prior of the Department of Mathematical Sciences, Durham University, will present the work today at the virtual National Astronomy Meeting (NAM 2021).

Researchers are generally in agreement that solar activity is caused by instabilities in giant twists of magnetic ropes threading the visible surface of the Sun, known as the photosphere. However, there has been an ongoing debate about how these tangles form. The two dominant theories have suggested either that coils of field lines emerge through the photosphere from the convection zone below, or that the feet of arching field lines wrap around each other on the surface itself and create braids. Both mechanisms could theoretically produce effects like sunspot rotation and dramatic solar flares but, to date, no direct observational evidence had conclusively supported either scenario.

Prior and colleagues from the University of Glasgow and INAF-Osservatorio Astrofisico di Catania in Italy came up with a new direct measure of the entanglement of the magnetic field by tracking the rotation of field lines at the points where they intersect with the photosphere. This ‘magnetic winding’ should manifest in different ways for each of the two theories. Thus, applying magnetic winding to observations of the photosphere and examining the resulting patterns could enable a definitive answer to be reached for which theory was correct.

The researchers studied the magnetic winding for 10 active regions on the Sun in recent observations from spacecraft, and found that the results matched the emergence theory of pre-twisted magnetic field lines rising up from the convection zone.

Prior explains: “The pattern for pre-twisted field lines exactly matched the observational data we considered initially, and this has since been found to be true for all data sets of active regions we have looked at so far. We anticipate that magnetic winding will become a staple quantity in the interpretation of magnetic field structure from observational data.”


Media contacts

Anita Heward
Royal Astronomical Society
Mob: +44 (0)7756 034 243

Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877 699

Dr Morgan Hollis
Royal Astronomical Society
Mob: +44 (0)7802 877 700

Vittoria D'Alessio
PR and Media Manager
University of Bath
Tel: +44 (0)1225 383 135


Science contacts

Dr Christopher Prior
Durham University


Images and captions

Simulation of twisted magnetic field lines emerging through the photosphere, the visible surface of the Sun.
D. MacTaggart et al.


Two images of solar magnetic flux ropes
Side-by-side comparison of magnetic flux ropes. The image on the left shows a series of magnetic loops on the sun, as captured by NASA's Solar Dynamics Observatory. The image on the right has been processed to highlight the edges of each loop and make the structure clearer.
NASA's Goddard Space Flight Center / SDO


Further information

The work appears in: 

  • "Direct evidence: twisted flux tube emergence creates solar active regions", D. MacTaggart, C. Prior, B. Raphaldini, P. Romano & S. Guglielmino (2021) (arXiv preprint)
  • "Magnetic winding: what is it and what is it good for?", C. Prior & D. MacTaggart, Proc. R. Soc. A., 476 (2242) (2020) (DOI: 10.1098/rspa.2020.0483)


Notes for editors

About the National Astronomy Meeting

The Royal Astronomical Society National Astronomy Meeting (NAM 2021) will take place online from 19 - 23 July 2021. Bringing together around 800 astronomers and space scientists, the conference is the largest annual professional astronomy and space science event in the UK, and sees leading researchers from around the world presenting their latest work.

NAM 2021 incorporates the annual meetings of the Magnetosphere Ionosphere Solar-Terrestrial (MIST) and UK Solar Physics (UKSP) groups. The conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and the University of Bath.

Follow NAM 2021 on Twitter


About the Royal Astronomical Society

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Follow the RAS on Twitter, Facebook, Instagram and YouTube

Download the RAS Supermassive podcast


About the Science and Technology Facilities Council

The Science and Technology Facilities Council is part of UK Research and Innovation – the UK body which works in partnership with universities, research organisations, businesses, charities, and government to create the best possible environment for research and innovation to flourish. STFC funds and supports research in particle and nuclear physics, astronomy, gravitational research and astrophysics, and space science and also operates a network of five national laboratories as well as supporting UK research at a number of international research facilities including CERN, FERMILAB and the ESO telescopes in Chile. STFC is keeping the UK at the forefront of international science and has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar.

STFC's Astronomy and Space Science programme provides support for a wide range of facilities, research groups and individuals in order to investigate some of the highest priority questions in astrophysics, cosmology and solar system science. STFC's astronomy and space science programme is delivered through grant funding for research activities, and also through support of technical activities at STFC's UK Astronomy Technology Centre and RAL Space at the Rutherford Appleton Laboratory. STFC also supports UK astronomy through the international European Southern Observatory.

Follow STFC on Twitter


About the University of Bath

The University of Bath is one of the UK's leading universities both in terms of research and our reputation for excellence in teaching, learning and graduate prospects.

The University is rated Gold in the Teaching Excellence Framework (TEF), the Government’s assessment of teaching quality in universities, meaning its teaching is of the highest quality in the UK.

In the Research Excellence Framework (REF) 2014 research assessment 87 per cent of our research was defined as ‘world-leading’ or ‘internationally excellent’. From developing fuel efficient cars of the future, to identifying infectious diseases more quickly, or working to improve the lives of female farmers in West Africa, research from Bath is making a difference around the world. Find out more

Well established as a nurturing environment for enterprising minds, Bath is ranked highly in all national league tables. We are ranked 6th in the UK by The Guardian University Guide 2021, and 9th in The Times & Sunday Times Good University Guide 2021 and 10th in the Complete University Guide 2021. Our sports offering was rated as being in the world’s top 10 in the QS World University Rankings by Subject in 2021.


About Durham University

Durham University is a globally outstanding centre of teaching and research based in historic Durham City in the UK. We are a collegiate university committed to inspiring our people to do outstanding things at Durham and in the world.

We conduct boundary-breaking research that improves lives globally and we are ranked as a world top 100 university with an international reputation in research and education (QS World University Rankings 2022).

We are a member of the Russell Group of leading research-intensive UK universities and we are consistently ranked as a top 10 university in national league tables (Times and Sunday Times Good University Guide, Guardian University Guide and The Complete University Guide).

For more information about Durham University visit: www.durham.ac.uk/about/


Submitted by Morgan Hollis on Thu, 22/07/2021 - 00:01